1 2 The Linux IPMI Driver
3 ---------------------
4 Corey Minyard
5 <minyard@mvista.com>
6 <minyard@acm.org>
7 8The Intelligent Platform Management Interface, or IPMI, is a
9standard for controlling intelligent devices that monitor a system.
10It provides for dynamic discovery of sensors in the system and the
11ability to monitor the sensors and be informed when the sensor's
12values change or go outside certain boundaries. It also has a
13standardized database for field-replaceable units (FRUs) and a watchdog
14timer.
15 16To use this, you need an interface to an IPMI controller in your
17system (called a Baseboard Management Controller, or BMC) and
18management software that can use the IPMI system.
19 20This document describes how to use the IPMI driver for Linux. If you
21are not familiar with IPMI itself, see the web site at
22http://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big
23subject and I can't cover it all here!
24 25Configuration
26-------------
27 28The Linux IPMI driver is modular, which means you have to pick several
29things to have it work right depending on your hardware. Most of
30these are available in the 'Character Devices' menu then the IPMI
31menu.
32 33No matter what, you must pick 'IPMI top-level message handler' to use
34IPMI. What you do beyond that depends on your needs and hardware.
35 36The message handler does not provide any user-level interfaces.
37Kernel code (like the watchdog) can still use it. If you need access
38from userland, you need to select 'Device interface for IPMI' if you
39want access through a device driver.
40 41The driver interface depends on your hardware. If your system
42properly provides the SMBIOS info for IPMI, the driver will detect it
43and just work. If you have a board with a standard interface (These
44will generally be either "KCS", "SMIC", or "BT", consult your hardware
45manual), choose the 'IPMI SI handler' option.
46 47You should generally enable ACPI on your system, as systems with IPMI
48can have ACPI tables describing them.
49 50If you have a standard interface and the board manufacturer has done
51their job correctly, the IPMI controller should be automatically
52detected (via ACPI or SMBIOS tables) and should just work. Sadly,
53many boards do not have this information. The driver attempts
54standard defaults, but they may not work. If you fall into this
55situation, you need to read the section below named 'The SI Driver'.
56 57IPMI defines a standard watchdog timer. You can enable this with the
58'IPMI Watchdog Timer' config option. If you compile the driver into
59the kernel, then via a kernel command-line option you can have the
60watchdog timer start as soon as it initializes. It also have a lot
61of other options, see the 'Watchdog' section below for more details.
62Note that you can also have the watchdog continue to run if it is
63closed (by default it is disabled on close). Go into the 'Watchdog
64Cards' menu, enable 'Watchdog Timer Support', and enable the option
65'Disable watchdog shutdown on close'.
66 67IPMI systems can often be powered off using IPMI commands. Select
68'IPMI Poweroff' to do this. The driver will auto-detect if the system
69can be powered off by IPMI. It is safe to enable this even if your
70system doesn't support this option. This works on ATCA systems, the
71Radisys CPI1 card, and any IPMI system that supports standard chassis
72management commands.
73 74If you want the driver to put an event into the event log on a panic,
75enable the 'Generate a panic event to all BMCs on a panic' option. If
76you want the whole panic string put into the event log using OEM
77events, enable the 'Generate OEM events containing the panic string'
78option.
79 80Basic Design
81------------
82 83The Linux IPMI driver is designed to be very modular and flexible, you
84only need to take the pieces you need and you can use it in many
85different ways. Because of that, it's broken into many chunks of
86code. These chunks (by module name) are:
87 88ipmi_msghandler - This is the central piece of software for the IPMI
89system. It handles all messages, message timing, and responses. The
90IPMI users tie into this, and the IPMI physical interfaces (called
91System Management Interfaces, or SMIs) also tie in here. This
92provides the kernelland interface for IPMI, but does not provide an
93interface for use by application processes.
94 95ipmi_devintf - This provides a userland IOCTL interface for the IPMI
96driver, each open file for this device ties in to the message handler
97as an IPMI user.
98 99ipmi_si - A driver for various system interfaces. This supports KCS,
100SMIC, and BT interfaces.
101 102ipmi_watchdog - IPMI requires systems to have a very capable watchdog
103timer. This driver implements the standard Linux watchdog timer
104interface on top of the IPMI message handler.
105 106ipmi_poweroff - Some systems support the ability to be turned off via
107IPMI commands.
108 109These are all individually selectable via configuration options.
110 111Note that the KCS-only interface has been removed. The af_ipmi driver
112is no longer supported and has been removed because it was impossible
113to do 32 bit emulation on 64-bit kernels with it.
114 115Much documentation for the interface is in the include files. The
116IPMI include files are:
117 118net/af_ipmi.h - Contains the socket interface.
119 120linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI.
121 122linux/ipmi_smi.h - Contains the interface for system management interfaces
123(things that interface to IPMI controllers) to use.
124 125linux/ipmi_msgdefs.h - General definitions for base IPMI messaging.
126 127 128Addressing
129----------
130 131The IPMI addressing works much like IP addresses, you have an overlay
132to handle the different address types. The overlay is:
133 134 struct ipmi_addr
135 {
136 int addr_type;
137 short channel;
138 char data[IPMI_MAX_ADDR_SIZE];
139 };
140 141The addr_type determines what the address really is. The driver
142currently understands two different types of addresses.
143 144"System Interface" addresses are defined as:
145 146 struct ipmi_system_interface_addr
147 {
148 int addr_type;
149 short channel;
150 };
151 152and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking
153straight to the BMC on the current card. The channel must be
154IPMI_BMC_CHANNEL.
155 156Messages that are destined to go out on the IPMB bus use the
157IPMI_IPMB_ADDR_TYPE address type. The format is
158 159 struct ipmi_ipmb_addr
160 {
161 int addr_type;
162 short channel;
163 unsigned char slave_addr;
164 unsigned char lun;
165 };
166 167The "channel" here is generally zero, but some devices support more
168than one channel, it corresponds to the channel as defined in the IPMI
169spec.
170 171 172Messages
173--------
174 175Messages are defined as:
176 177struct ipmi_msg
178{
179 unsigned char netfn;
180 unsigned char lun;
181 unsigned char cmd;
182 unsigned char *data;
183 int data_len;
184};
185 186The driver takes care of adding/stripping the header information. The
187data portion is just the data to be send (do NOT put addressing info
188here) or the response. Note that the completion code of a response is
189the first item in "data", it is not stripped out because that is how
190all the messages are defined in the spec (and thus makes counting the
191offsets a little easier :-).
192 193When using the IOCTL interface from userland, you must provide a block
194of data for "data", fill it, and set data_len to the length of the
195block of data, even when receiving messages. Otherwise the driver
196will have no place to put the message.
197 198Messages coming up from the message handler in kernelland will come in
199as:
200 201 struct ipmi_recv_msg
202 {
203 struct list_head link;
204 205 /* The type of message as defined in the "Receive Types"
206 defines above. */
207 int recv_type;
208 209 ipmi_user_t *user;
210 struct ipmi_addr addr;
211 long msgid;
212 struct ipmi_msg msg;
213 214 /* Call this when done with the message. It will presumably free
215 the message and do any other necessary cleanup. */
216 void (*done)(struct ipmi_recv_msg *msg);
217 218 /* Place-holder for the data, don't make any assumptions about
219 the size or existence of this, since it may change. */
220 unsigned char msg_data[IPMI_MAX_MSG_LENGTH];
221 };
222 223You should look at the receive type and handle the message
224appropriately.
225 226 227The Upper Layer Interface (Message Handler)
228-------------------------------------------
229 230The upper layer of the interface provides the users with a consistent
231view of the IPMI interfaces. It allows multiple SMI interfaces to be
232addressed (because some boards actually have multiple BMCs on them)
233and the user should not have to care what type of SMI is below them.
234 235 236Creating the User
237 238To user the message handler, you must first create a user using
239ipmi_create_user. The interface number specifies which SMI you want
240to connect to, and you must supply callback functions to be called
241when data comes in. The callback function can run at interrupt level,
242so be careful using the callbacks. This also allows to you pass in a
243piece of data, the handler_data, that will be passed back to you on
244all calls.
245 246Once you are done, call ipmi_destroy_user() to get rid of the user.
247 248From userland, opening the device automatically creates a user, and
249closing the device automatically destroys the user.
250 251 252Messaging
253 254To send a message from kernel-land, the ipmi_request() call does
255pretty much all message handling. Most of the parameter are
256self-explanatory. However, it takes a "msgid" parameter. This is NOT
257the sequence number of messages. It is simply a long value that is
258passed back when the response for the message is returned. You may
259use it for anything you like.
260 261Responses come back in the function pointed to by the ipmi_recv_hndl
262field of the "handler" that you passed in to ipmi_create_user().
263Remember again, these may be running at interrupt level. Remember to
264look at the receive type, too.
265 266From userland, you fill out an ipmi_req_t structure and use the
267IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select()
268or poll() to wait for messages to come in. However, you cannot use
269read() to get them, you must call the IPMICTL_RECEIVE_MSG with the
270ipmi_recv_t structure to actually get the message. Remember that you
271must supply a pointer to a block of data in the msg.data field, and
272you must fill in the msg.data_len field with the size of the data.
273This gives the receiver a place to actually put the message.
274 275If the message cannot fit into the data you provide, you will get an
276EMSGSIZE error and the driver will leave the data in the receive
277queue. If you want to get it and have it truncate the message, us
278the IPMICTL_RECEIVE_MSG_TRUNC ioctl.
279 280When you send a command (which is defined by the lowest-order bit of
281the netfn per the IPMI spec) on the IPMB bus, the driver will
282automatically assign the sequence number to the command and save the
283command. If the response is not receive in the IPMI-specified 5
284seconds, it will generate a response automatically saying the command
285timed out. If an unsolicited response comes in (if it was after 5
286seconds, for instance), that response will be ignored.
287 288In kernelland, after you receive a message and are done with it, you
289MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note
290that you should NEVER mess with the "done" field of a message, that is
291required to properly clean up the message.
292 293Note that when sending, there is an ipmi_request_supply_msgs() call
294that lets you supply the smi and receive message. This is useful for
295pieces of code that need to work even if the system is out of buffers
296(the watchdog timer uses this, for instance). You supply your own
297buffer and own free routines. This is not recommended for normal use,
298though, since it is tricky to manage your own buffers.
299 300 301Events and Incoming Commands
302 303The driver takes care of polling for IPMI events and receiving
304commands (commands are messages that are not responses, they are
305commands that other things on the IPMB bus have sent you). To receive
306these, you must register for them, they will not automatically be sent
307to you.
308 309To receive events, you must call ipmi_set_gets_events() and set the
310"val" to non-zero. Any events that have been received by the driver
311since startup will immediately be delivered to the first user that
312registers for events. After that, if multiple users are registered
313for events, they will all receive all events that come in.
314 315For receiving commands, you have to individually register commands you
316want to receive. Call ipmi_register_for_cmd() and supply the netfn
317and command name for each command you want to receive. You also
318specify a bitmask of the channels you want to receive the command from
319(or use IPMI_CHAN_ALL for all channels if you don't care). Only one
320user may be registered for each netfn/cmd/channel, but different users
321may register for different commands, or the same command if the
322channel bitmasks do not overlap.
323 324From userland, equivalent IOCTLs are provided to do these functions.
325 326 327The Lower Layer (SMI) Interface
328-------------------------------
329 330As mentioned before, multiple SMI interfaces may be registered to the
331message handler, each of these is assigned an interface number when
332they register with the message handler. They are generally assigned
333in the order they register, although if an SMI unregisters and then
334another one registers, all bets are off.
335 336The ipmi_smi.h defines the interface for management interfaces, see
337that for more details.
338 339 340The SI Driver
341-------------
342 343The SI driver allows up to 4 KCS or SMIC interfaces to be configured
344in the system. By default, scan the ACPI tables for interfaces, and
345if it doesn't find any the driver will attempt to register one KCS
346interface at the spec-specified I/O port 0xca2 without interrupts.
347You can change this at module load time (for a module) with:
348 349 modprobe ipmi_si.o type=<type1>,<type2>....
350 ports=<port1>,<port2>... addrs=<addr1>,<addr2>...
351 irqs=<irq1>,<irq2>...
352 regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,...
353 regshifts=<shift1>,<shift2>,...
354 slave_addrs=<addr1>,<addr2>,...
355 force_kipmid=<enable1>,<enable2>,...
356 kipmid_max_busy_us=<ustime1>,<ustime2>,...
357 unload_when_empty=[0|1]
358 trydefaults=[0|1] trydmi=[0|1] tryacpi=[0|1]
359 tryplatform=[0|1] trypci=[0|1]
360 361Each of these except try... items is a list, the first item for the
362first interface, second item for the second interface, etc.
363 364The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it
365defaults to "kcs".
366 367If you specify addrs as non-zero for an interface, the driver will
368use the memory address given as the address of the device. This
369overrides si_ports.
370 371If you specify ports as non-zero for an interface, the driver will
372use the I/O port given as the device address.
373 374If you specify irqs as non-zero for an interface, the driver will
375attempt to use the given interrupt for the device.
376 377trydefaults sets whether the standard IPMI interface at 0xca2 and
378any interfaces specified by ACPE are tried. By default, the driver
379tries it, set this value to zero to turn this off.
380 381The other try... items disable discovery by their corresponding
382names. These are all enabled by default, set them to zero to disable
383them. The tryplatform disables openfirmware.
384 385The next three parameters have to do with register layout. The
386registers used by the interfaces may not appear at successive
387locations and they may not be in 8-bit registers. These parameters
388allow the layout of the data in the registers to be more precisely
389specified.
390 391The regspacings parameter give the number of bytes between successive
392register start addresses. For instance, if the regspacing is set to 4
393and the start address is 0xca2, then the address for the second
394register would be 0xca6. This defaults to 1.
395 396The regsizes parameter gives the size of a register, in bytes. The
397data used by IPMI is 8-bits wide, but it may be inside a larger
398register. This parameter allows the read and write type to specified.
399It may be 1, 2, 4, or 8. The default is 1.
400 401Since the register size may be larger than 32 bits, the IPMI data may not
402be in the lower 8 bits. The regshifts parameter give the amount to shift
403the data to get to the actual IPMI data.
404 405The slave_addrs specifies the IPMI address of the local BMC. This is
406usually 0x20 and the driver defaults to that, but in case it's not, it
407can be specified when the driver starts up.
408 409The force_ipmid parameter forcefully enables (if set to 1) or disables
410(if set to 0) the kernel IPMI daemon. Normally this is auto-detected
411by the driver, but systems with broken interrupts might need an enable,
412or users that don't want the daemon (don't need the performance, don't
413want the CPU hit) can disable it.
414 415If unload_when_empty is set to 1, the driver will be unloaded if it
416doesn't find any interfaces or all the interfaces fail to work. The
417default is one. Setting to 0 is useful with the hotmod, but is
418obviously only useful for modules.
419 420When compiled into the kernel, the parameters can be specified on the
421kernel command line as:
422 423 ipmi_si.type=<type1>,<type2>...
424 ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>...
425 ipmi_si.irqs=<irq1>,<irq2>... ipmi_si.trydefaults=[0|1]
426 ipmi_si.regspacings=<sp1>,<sp2>,...
427 ipmi_si.regsizes=<size1>,<size2>,...
428 ipmi_si.regshifts=<shift1>,<shift2>,...
429 ipmi_si.slave_addrs=<addr1>,<addr2>,...
430 ipmi_si.force_kipmid=<enable1>,<enable2>,...
431 ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,...
432 433It works the same as the module parameters of the same names.
434 435By default, the driver will attempt to detect any device specified by
436ACPI, and if none of those then a KCS device at the spec-specified
4370xca2. If you want to turn this off, set the "trydefaults" option to
438false.
439 440If your IPMI interface does not support interrupts and is a KCS or
441SMIC interface, the IPMI driver will start a kernel thread for the
442interface to help speed things up. This is a low-priority kernel
443thread that constantly polls the IPMI driver while an IPMI operation
444is in progress. The force_kipmid module parameter will all the user to
445force this thread on or off. If you force it off and don't have
446interrupts, the driver will run VERY slowly. Don't blame me,
447these interfaces suck.
448 449Unfortunately, this thread can use a lot of CPU depending on the
450interface's performance. This can waste a lot of CPU and cause
451various issues with detecting idle CPU and using extra power. To
452avoid this, the kipmid_max_busy_us sets the maximum amount of time, in
453microseconds, that kipmid will spin before sleeping for a tick. This
454value sets a balance between performance and CPU waste and needs to be
455tuned to your needs. Maybe, someday, auto-tuning will be added, but
456that's not a simple thing and even the auto-tuning would need to be
457tuned to the user's desired performance.
458 459The driver supports a hot add and remove of interfaces. This way,
460interfaces can be added or removed after the kernel is up and running.
461This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a
462write-only parameter. You write a string to this interface. The string
463has the format:
464 <op1>[:op2[:op3...]]
465The "op"s are:
466 add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]]
467You can specify more than one interface on the line. The "opt"s are:
468 rsp=<regspacing>
469 rsi=<regsize>
470 rsh=<regshift>
471 irq=<irq>
472 ipmb=<ipmb slave addr>
473and these have the same meanings as discussed above. Note that you
474can also use this on the kernel command line for a more compact format
475for specifying an interface. Note that when removing an interface,
476only the first three parameters (si type, address type, and address)
477are used for the comparison. Any options are ignored for removing.
478 479 480Other Pieces
481------------
482 483Get the detailed info related with the IPMI device
484--------------------------------------------------
485 486Some users need more detailed information about a device, like where
487the address came from or the raw base device for the IPMI interface.
488You can use the IPMI smi_watcher to catch the IPMI interfaces as they
489come or go, and to grab the information, you can use the function
490ipmi_get_smi_info(), which returns the following structure:
491 492struct ipmi_smi_info {
493 enum ipmi_addr_src addr_src;
494 struct device *dev;
495 union {
496 struct {
497 void *acpi_handle;
498 } acpi_info;
499 } addr_info;
500};
501 502Currently special info for only for SI_ACPI address sources is
503returned. Others may be added as necessary.
504 505Note that the dev pointer is included in the above structure, and
506assuming ipmi_smi_get_info returns success, you must call put_device
507on the dev pointer.
508 509 510Watchdog
511--------
512 513A watchdog timer is provided that implements the Linux-standard
514watchdog timer interface. It has three module parameters that can be
515used to control it:
516 517 modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type>
518 preaction=<preaction type> preop=<preop type> start_now=x
519 nowayout=x ifnum_to_use=n
520 521ifnum_to_use specifies which interface the watchdog timer should use.
522The default is -1, which means to pick the first one registered.
523 524The timeout is the number of seconds to the action, and the pretimeout
525is the amount of seconds before the reset that the pre-timeout panic will
526occur (if pretimeout is zero, then pretimeout will not be enabled). Note
527that the pretimeout is the time before the final timeout. So if the
528timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout
529will occur in 40 second (10 seconds before the timeout).
530 531The action may be "reset", "power_cycle", or "power_off", and
532specifies what to do when the timer times out, and defaults to
533"reset".
534 535The preaction may be "pre_smi" for an indication through the SMI
536interface, "pre_int" for an indication through the SMI with an
537interrupts, and "pre_nmi" for a NMI on a preaction. This is how
538the driver is informed of the pretimeout.
539 540The preop may be set to "preop_none" for no operation on a pretimeout,
541"preop_panic" to set the preoperation to panic, or "preop_give_data"
542to provide data to read from the watchdog device when the pretimeout
543occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data"
544because you can't do data operations from an NMI.
545 546When preop is set to "preop_give_data", one byte comes ready to read
547on the device when the pretimeout occurs. Select and fasync work on
548the device, as well.
549 550If start_now is set to 1, the watchdog timer will start running as
551soon as the driver is loaded.
552 553If nowayout is set to 1, the watchdog timer will not stop when the
554watchdog device is closed. The default value of nowayout is true
555if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not.
556 557When compiled into the kernel, the kernel command line is available
558for configuring the watchdog:
559 560 ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t>
561 ipmi_watchdog.action=<action type>
562 ipmi_watchdog.preaction=<preaction type>
563 ipmi_watchdog.preop=<preop type>
564 ipmi_watchdog.start_now=x
565 ipmi_watchdog.nowayout=x
566 567The options are the same as the module parameter options.
568 569The watchdog will panic and start a 120 second reset timeout if it
570gets a pre-action. During a panic or a reboot, the watchdog will
571start a 120 timer if it is running to make sure the reboot occurs.
572 573Note that if you use the NMI preaction for the watchdog, you MUST NOT
574use the nmi watchdog. There is no reasonable way to tell if an NMI
575comes from the IPMI controller, so it must assume that if it gets an
576otherwise unhandled NMI, it must be from IPMI and it will panic
577immediately.
578 579Once you open the watchdog timer, you must write a 'V' character to the
580device to close it, or the timer will not stop. This is a new semantic
581for the driver, but makes it consistent with the rest of the watchdog
582drivers in Linux.
583 584 585Panic Timeouts
586--------------
587 588The OpenIPMI driver supports the ability to put semi-custom and custom
589events in the system event log if a panic occurs. if you enable the
590'Generate a panic event to all BMCs on a panic' option, you will get
591one event on a panic in a standard IPMI event format. If you enable
592the 'Generate OEM events containing the panic string' option, you will
593also get a bunch of OEM events holding the panic string.
594 595 596The field settings of the events are:
597* Generator ID: 0x21 (kernel)
598* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format)
599* Sensor Type: 0x20 (OS critical stop sensor)
600* Sensor #: The first byte of the panic string (0 if no panic string)
601* Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info)
602* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3)
603* Event data 2: second byte of panic string
604* Event data 3: third byte of panic string
605See the IPMI spec for the details of the event layout. This event is
606always sent to the local management controller. It will handle routing
607the message to the right place
608 609Other OEM events have the following format:
610Record ID (bytes 0-1): Set by the SEL.
611Record type (byte 2): 0xf0 (OEM non-timestamped)
612byte 3: The slave address of the card saving the panic
613byte 4: A sequence number (starting at zero)
614The rest of the bytes (11 bytes) are the panic string. If the panic string
615is longer than 11 bytes, multiple messages will be sent with increasing
616sequence numbers.
617 618Because you cannot send OEM events using the standard interface, this
619function will attempt to find an SEL and add the events there. It
620will first query the capabilities of the local management controller.
621If it has an SEL, then they will be stored in the SEL of the local
622management controller. If not, and the local management controller is
623an event generator, the event receiver from the local management
624controller will be queried and the events sent to the SEL on that
625device. Otherwise, the events go nowhere since there is nowhere to
626send them.
627 628 629Poweroff
630--------
631 632If the poweroff capability is selected, the IPMI driver will install
633a shutdown function into the standard poweroff function pointer. This
634is in the ipmi_poweroff module. When the system requests a powerdown,
635it will send the proper IPMI commands to do this. This is supported on
636several platforms.
637 638There is a module parameter named "poweroff_powercycle" that may
639either be zero (do a power down) or non-zero (do a power cycle, power
640the system off, then power it on in a few seconds). Setting
641ipmi_poweroff.poweroff_control=x will do the same thing on the kernel
642command line. The parameter is also available via the proc filesystem
643in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system
644does not support power cycling, it will always do the power off.
645 646The "ifnum_to_use" parameter specifies which interface the poweroff
647code should use. The default is -1, which means to pick the first one
648registered.
649 650Note that if you have ACPI enabled, the system will prefer using ACPI to
651power off.
652